Which of the following macromolecules describe a typicadv* 7,s mz,pjal enzyme?

  What type of reaction is photosynthesi-tjni wytu)48m x 6kh7s?

  What is the substrate for the enecq 1e3lpoegl4 (a mq57ix3;-a/z qlazyme lactase?

  Which of the following stages of cellular respiratiqt;8* x0yzz uu urci t-716qwyon takes place in the cytoplasm?;zqzuy8tu 16qxiryuw0t7*c -

  Which of the following would not be usefuy*yny5;uh 5pg ol72r ul in determining the rate of an enzyme-catalyzedu ny;r57 pl*g yu5oh2y reaction?

  Which of the following processes may be described as catabolism?*9ogcek oo4d n hy142v

  Which of the following statementse,3dugsz)*p pem3 ed2mw ( vl4 is best depicted by the figure below?

  Which statement about enzymes is not tr2)ug1w nmm rl,ue?

  Which of the following graphs best illustrates the relationship 9.slbz6t88js5 tp m tzbetween temperature and the activity of enzyme tst tp z5lmb.698z8jss such as lipase?

1.Sketch a graph to show how increask(-f-s jt1ftf q,8ud c5twj:e ing concentrations of substrate affect enzyme actit--18fc,jweustf(5 q:dkft jvity.
2.Explain how the addition of a competitive inhibitor changes the activity of an enzyme.

  The Calvin cycle is a series of enzyme catalysed reactions. A diagram outli:kg x2 syzl6f1sm165 lrnt*plning the Calvin cycle iszkgnl52l6lyxtfs m6 11r:p* s shown below.

The image below shows the ca/ jvqmvy4 cf wf; f;6v(uvi9(jtalytic site of an enzyme. The substrate is shown in black and is bound to the actv;(vfqj/c6vj (w i94vmf u y;five site.





1.State how the activation energy is changed by adding an enzyme to a reaction.
2.Distinguish between anabolic and catabolic pathways.

  Which are correct descriptions of the enzyme catalysed metabolic f2xk)nl8kvs 8pathways shown below? Letters represent various products of indiv8n lfkk82xsv) idual reactions.

  Which of the following describes the role of inhibitors in/mwk d 2+mm4jqs1g9r f enzyme-catalysed reactg2swmm 4k9f/qjm1r+dions?

  Which of the following correctly describes photosyb sv/; l:vel1knthesis or respiration?

Many enzymatic reactions happen as pathways involving multiple stepe1u gxq7 iz3xg i3z1e-s and multiple enzyme3uz1iei x gxzq-7e1 g3s.

1.Describe how enzymes catalyze reactions.
2.Outline the advantages of enzyme-substrate specificity.

  Which of the following best describes the inhibitor in th(4p o j/zjv*kfe image below?

  Which of the following statements are true regarding rcyc0wbgx+ j-13fb j0yegulation by end-product inhibition? +0jwbjgfyc3b1y- xc0
I. The end product binds to the allosteric site of the enzyme.
II. The binding of the end product is reversible.
III.End product inhibition is an example of negative feedback regulation.

  The following image shows the strjlwdw -b.y+n gptnf 3 bzz7/gq9k84f5ucture of the lysozyme enzyme. The darkened structure in black is the substrate and is 5nz93q.lydb /pb 8-7z+ff wjk4g gwtnbound at the active site.

Which of the following characterizes the active site of an enzyme?

The equipment below c0*(em,b vpp- tagz)hean be used to study the effect of temperature on the activity of tt p,-ephmbea()v 0*gzhe enzyme amylase.



1.Outline how this equipment could be used to set up a study into the effect of temperature on amylase activity, up to the point of getting the results.
2.Outline how the rate of reaction of the breakdown of starch by amylase could be measured using the equipment given.
3.Describe a suitable control experiment for this study.
4.Suggest one way to increase the reliability of the data that can be gathered from this experiment.
5.Using the axis below draw a graph of the expected results from the study in part (a).

  Which of the following statements describes z+ +(bmt 4vu80vqkfhu how enzymes interact with substrates to catafbvz k8u+4m+ u (q0htvlyze reactions?
I. Enzymes and substrates in solutions collide with one another, and the substrate is bound at the active site.
II. There is more movement of the substrate in a reaction because the substrate is usually smaller than the enzyme in size.
III.When the substrate binds to the active site, the shape of the enzyme changes slightly so it can accommodate the substrate.

Outline two ways enzyme catalysed reactions can bntrp3lx t:m m5toaagz 81n+l /*l 7cm0e measured.

  How does denaturation changef 2an3nf sp0;zk -iz;mz09kr;p;jym 7pk h6 rw the properties of an enzyme?

  Enzymes play a role in catalysing reactions. Which of the following s( r/h*n4p+3cf1u i pjn c.hg ckc)h0qqtatements are true? chkcihcnc 0n/4 3*fug(.+pqh1rjp ) q
I.The substrate is temporarily provided with energy before being converted to a product.
II. Enzymes reduce the activation energy needed for the reaction.
III.The active site binds to the substrate making it easier for bonds to be broken or formed.

  What is a characteristic that separates mk9 k ekqwf2 tc*;6xvc*ammals or endotherms from ectotherms that ha*9c2 k;f kqt c6vek*wxve fluctuating body temperatures?

  A metabolic pathway that converts threonine to the end-product isoleucine cog0q2-w wn7 vxtnsists of five reactions. Threonine is converted to various intq20- ntxw7vwgermediate products sequentially by different enzymes before it is converted to isoleucine by the last enzyme in the pathway.
In the following diagram, the enzymes have been labelled as E1, E2, E3, E4 and E5.


Which of the following shows how this pathway is regulated?

  The graph shows the effect of increasing pH on the rate of an enzymatic)(u5+61b.nbyqlxne k;yjg .cuf i8 lv reaction. What 1.bgni jvnl;yukelfu )x c(85+yq6b .is occurring during the phase labelled section X in the graph?

  An experiment tests the effect of changing substrate concentrati1 90iymr l73t s0;lpc jbjah:bon on an enzymatic reaction. What could be the independent and dependent variables in this experiment rlh07:;jit0a31 m9y bsbjlcp?

  The diagram shows the pathway that converts threoni fbrhbvmx02 el q-4*t9ne to isoleucine.



What is the name and mechanism of the process through which isoleucine interacts with threonine dehydratase?

  Enzyme A (Enz A) was immobilized on a matrix and its activity was+o 8qqapox-yxo*, xl( compared with that of a free enzyme in solution. The graph shows the relative enzyme activity (y-axis) with varying pH (x-axxaop(oxq,ly + 8o*-x qis).



Which of the following statements is true?
I. Both soluble and immobilized enzymes are inactive at higher pH values of 8.
II. The immobilized Enz A is more resistant to pH changes showing more activity than the soluble enzyme at most tested pH values.
III. Immobilizing Enz A did not decrease its catalytic activity.

  Purified enzymes are easily denatured. Which of the followingfm ot4 k:,r-bt is the best way to t,o: -fm r4tbkkeep enzymes active for a longer period of time?

  Which of the following describes some typeshzy( be1 ,uka: of extracellular enzymes?

  The enzyme pepsin hydrolyses proteins to release peptides l ,0fe43b )bixkrhf e. nsaaoa/j h6((in the stomach. A study was carried out to determine the effect of increasing substrate concentration on enzyme activity at a constant temperature osal( r( ihna4f3j,fehx.k0) b a 6b/eof $30{\circ}C.

1.Describe the trends shown by the graph.
2. 1.Outline why it is important that temperature is kept constant in this experiment.
2.State one factor other than temperature that would need to be controlled in this experiment.
3.Suggest a method that can be used to maintain a constant temperature in this experiment.
3.Calculate the rate of reaction during the first 4 minutes when the enzyme pepsin is exposed to 5 mM of protein. Make sure you show your working. ----待选择----+-   
4.Explain the observed results.

  The graph below shows the rate of reaction of an enzyme with increasingso* z2b82mt kd substrate co22 tk bsom8*dzncentration. Similar concentrations of chemicals A, B, C and D were added independently to the reaction, and the activity was monitored for each of the reactions. The curve marked A coincides with the activity of the enzyme with no inhibitor added.
Which of the chemicals is likely to be a non-competitive inhibitor?

  To study catalase enzyme activity, a studfl 99f +1pxatnent cut a turnip root into small cubes. They measured approximately 5 g in a weighing dish, added 50 ml water and used a blender to homogenize the turnip root. The homogenate was filteretfal199 xfpn +d and the liquid extract was stored in a test tube at room temperature.


The turnip extract and water were added to the conical flask first. Then 3% hydrogen peroxide solution was added to the conical flask, as shown in the image above. The oxygen produced is collected over 1 minute and measured in an inverted measuring cylinder, as shown.
The student wanted to conduct an experiment to see the effect of increasing enzyme concentration on the reaction. She made up the different concentrations as shown in the table below and added 1 ml of 3% hydrogen peroxide to each.

1.Suggest why the process of grinding the turnip root and extracting the filtrate was carried out.
2.State the dependent variable.
3.Explain why the volume of water was varied, as shown.
The following graph was obtained when the student varied the substrate (hydrogen peroxide) concentration, keeping the enzyme concentration constant.



4.From the graph shown above, calculate the percentage increase in volume of oxygen gas produced when using 1% hydrogen peroxide compared to 0.5% hydrogen peroxide.  %
5.Outline the reasons for the shape of the curve obtained.
The student repeated the same experiment but added an inhibitor along with the enzyme to the reaction mix. She got the following results.


6.Deduce, with an explanation, whether a competitive or non-competitive inhibitor was used in the investigation.
7.Other than the factors already mentioned, state one other factor that can lower the rate of an enzyme controlled reaction.

  The mevalonate pathway is shownrc) yd(lltntc4mi:n yp xa9i/ 6g4e*. below. Inhibitors to the enzyme HMG- CoA reductase can lower the product6.(xc/4 irmln)yc9pt aldnte4*: gi yion of cholesterol.


Statins lower cholesterol, reduce the risk of heart attacks, and prevent strokes. They are known to inhibit HMG-CoA reductase, which is the rate-limiting enzyme of cholesterol biosynthesis in the mevalonate pathway (image above).
Which of the following describes the mechanism of action of statins in lowering cholesterol?

  Which of the following are involved i 3)rv utkpg3i*(wloh4n denaturation?
I.A change to the three dimensional structure of the protein
II. A change in the amino acid sequence of the protein
III. Changes in the properties of the protein

  Students were investigating metabolic reactio:s 47 srvliv8 gq,i-ewns in the classroom and were given an experim 7v-,sl vw8isi4eqrg:ent which demonstrated the effect of temperature on a catabolic reaction.
A sample of fat was added to a beaker, which contained 150ml of a 1% sodium chloride solution.


The beaker and its contents were then added to a water bath, which was set at 15
o
C. The beaker was given 5 minutes to equalise with the temperature of the water bath. After 5 minutes, 5 ml of a 2 % lipase solution, at the same temperature as the water bath, was added to the beaker.


5 ml of 2 % sodium hydroxide (NaOH), pH 8.4, was added to a test tube and phenolphthalein, a colourless solution which turns pink in basic environments, was then added. The intensity of the pink colour is proportionate to the strength of the basic solution.
At exactly 20 minutes, a 5ml sample was taken from the beaker incubated in the water bath and added to the test tube.

The contents of the test tube were then immediately transferred into a cuvette and placed in a spectrophotometer set at 420 nm. The percentage transmission of light able to pass through the sample was measured and recorded.

The procedure was then repeated using water baths set at a range of different temperatures. The measurements were recorded in a table and presented in a graph.



1. 1.State the independent variable in this experiment.
2.Identify two factors, not already mentioned, that would need to be controlled in this experiment
2. 1.Explain how the spectrophotometer is able to measure the breakdown of fat.
2.Explain the effect of increasing the temperature from 15
o
C to 35
o
C on the rate of the catabolic reaction.
3.Predict the percentage transmission for a sample incubated at 20
o
C.  %
4.Evaluate the claim that based on the data, the optimum temperature for lipase activity is 35
o
C.

  In an experiment, the effect of increasing tei y:chj:*bc0cow,,v-2r p tbu)zv,at mperature on the efficiency of lactase activity is tested. Which is an approprp,oic ,-ucab,): zv*ry j2t0:tvwbch iate dependent variable for this experiment?

  A study has been conducted ox7oyzri xnpv 2hncy, o1z6),/8)bagin the activity of a specific lactase (Bg10), analysing the effect of pH, temperature and glucose concentration, as it may potentially be use1 yphixbgn8) ,arn,/zzo)x2v7o6i c yd as a commercial lactase to produce lactose-free milk.



1.Deduce which temperature used in this experiment was the optimum one for the enzyme Bg10. Give a reason for your answer.
2.Explain the change in enzyme activity at temperatures above $40^{\circ}C$.
3.Evaluate whether the data supports the claim that the optimum pH for the lactase enzyme Bg10 is 7.

4.Calculate the percentage difference in relative activity of the enzyme Bg10 when treated with 500 mM of glucose compared to 50 mM of glucose. Make sure you show your working.  %

Further studies have been conducted on other lactase enzymes to test their thermal stability at an optimum temperature of 60°C, when they are immobilised on graphene nanosheets, in comparison to lactase enzymes floating freely in milk.

5.Compare the trend shown by the immobilised enzyme to that of the soluble enzyme.
6.Calculate the range of data for the soluble enzyme over 10 minutes.  log %

The storage stability at room temperature of the immobilised enzymes has also been compared to lactase enzymes floating freely in milk.


7.Compare and contrast the storage stability of the immobilised and free soluble enzyme.

The reusability of the immobilised enzyme was tested, by analysing the activity of the immobilised enzyme over 10 uses.


8.State one advantage of being able to reuse immobilised enzymes.
9.Using the data provided, and your own knowledge, suggest why immobilised enzymes should be used to make lactose free milk.

1.There is a continuous need to find new drugsi;c;i-)tfs ( augdw7b9 f5jpp for treating patients with malaria. Describe how anti-malarial drugs are being discovered with ne-b(if stw )a9;f 5p7d pj;gciuw technologies.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.

1.Explain how increasing the concentration of an enzymu s3ohq/;u5l be affects the rate of reaction. lb uu5soh 3q;/
2.Lactase converts lactose to glucose and galactose. Outline how lactase is used in the food industry.
3.Discuss the industrial use of immobilized enzymes using a named example.

  Biomolecules can be broken down or synthesized throug:pys8nx6oqp0w,p;jl -t1 vtx h metabolic reactions. Which type(s) of metabolic reactions are con p6p10qs t,vx:l8xn wyp; otj-densation reactions?
I. Hydrolysis
II. Catabolic
III.Anabolic

1.Outline the different ways tlz: +tazg6k)ae a(p/l he rate of enzyme catalyzed reactions can be measur+)/aap(t a6 z:ezlg lked.
2.Draw a graph to show the effect of temperature on the reaction rate of an enzyme.


3.State how the optimum temperature can be determined using the graph drawn in part b.

1.Compare and contrast intracellular and extracelc f8pc-hol57)jv f+ c-f9onmrlular chemical reactions, given one example of each type of reactrcm-o njfff- lov)c7c h98p+5ion.
2.Enzymes are regulated by inhibitors that are classified as competitive or non-competitive. Distinguish between these two types of inhibitors.
3.Describe, using an example, how metabolic pathways can be regulated by end-product inhibition.